Preparation of superhydrophobic nanocalcite crystals using Box–Behnken design

Journal of Colloid and Interface Science

El-Maghrabi

Iatsunskyi

et al. 2020

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h i g h l i g h t sSelf-supported CNF-Ni/NiO-Pd electrodes were fabricated. Electrospinning with atomic layer deposition were used for the electrode fabrication. CNF-Ni/NiO-Pd electrodes were used for HER and OER reactions under acidic and basic conditions. CNF-Ni/NiO-Pd electrodes have shown high HER and OER activity compared to Pt and IrO 2 catalysts. Synergistic effect between the graphitic nanosheets, Ni/NiO and Pd NPs at the nanointerfaces has been highlighted.

Section: Tablementioning

confidence: 99%

Atomic layer deposition of Pd nanoparticles on self-supported carbon-Ni/NiO-Pd nanofiber electrodes for electrochemical hydrogen and oxygen evolution reactions

Journal of Colloid and Interface Science

El-Maghrabi

Iatsunskyi

et al. 2020

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“…In view of this, it is essential to produce well-defined NPs and nanostructures with desired characteristics, to understand their formation and growth mechanisms, and to define the critical size below which they act differently from bulk materials in order to develop synthetic strategies [3]. For example, quantum dots (below 20 nm) are mainly single nanocrystals characterized by a single-domain crystalline lattice without grain boundaries [4,5]. These tiny individual crystals differ drastically from bulk polycrystalline materials [6].…”

Section: Introductionmentioning

confidence: 99%

Theories of nanoparticle and nanostructure formation in liquid phase

Karatutlu

Emerging Applications of Nanoparticles and Architecture Nanostructures

Sapelkin

2018

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598 CHAPTER 20 Theories of nanoparticle and nanostructure formation in liquid phase and crystallization. In general, tiny NP "clusters" are gathered together to form NPs, and then the NPs are assembled to form nanostructures. In bottom-up approaches, cluster formation and nucleation are the first steps in NP formation, and they are the most crucial steps in controlling the crystal structure, size, shape, and surface characteristics of NPs [9]. Nucleation is the process whereby nuclei (seeds) act as templates for crystal growth. Nucleation may happen in the solution homogeneously or heterogeneously. Homogeneous nucleation occurs when nuclei form uniformly within the parent phase, whereas heterogeneous nucleation forms on a solid support (nucleating surface), such as container surfaces, impurities, grain boundaries, or dislocations [10]. In general, heterogeneous nucleation occurs much more easily than homogenous nucleation, since a stable nucleating surface is already present.The fundamental phenomena involved in crystallization from solutions via nucleation and growth is still a hot topic [11]. Recently, significant efforts have been directed to understanding the mechanism of NP formation in solutions [12][13][14]. In particular, attention has been directed to study the wide varieties of additives and their influences on prenucleation clusters, nucleation, crystallization, nanocrystal assembly, and thus morphologies.The importance of NPs and nanostructures in many fields of science and technology has spurred a high level of research activity and led to the formulation of well-established theories for nucleation and crystal growth. This chapter highlights the different theories, such as classical nucleation theory (CNT), La Mer's nucleation and growth mechanisms, the two-step nucleation and growth mechanism, and the prenucleation cluster (PNC) mechanism. Subsequently in situ experimental characterization for NP formation, including nucleation and growth processes, will be highlighted, and what occurs within the different processes outlined. ■ ■ FIGURE 20.9 (A) The processes of Au depositing on a Pt icosahedral nanocrystal is schematically demonstrated. (B) The nucleation and growth of Au on Pt nanocrystals are quantitatively analyzed. (Source: Reproduced with permission from Ref. [47]. 615 6 In situ characterization techniques ■ ■ FIGURE 20.10 Radius, concentration, and size distribution from the SAXS fitting results. (A) The results of the fit of the SAXS patterns are presented as a function of time. For the two different ligands, the concentration of particles (n/N A ), the center of the Gaussian distribution, and the σ parameter are designated. (B) SAXS patterns for the first instants of the reaction and the corresponding fits for an acid ligand are shown. (C) Corresponding size distribution is given for the SAXS patterns presented in (B). (Source: Reproduced with permission from Ref. [48].

“…These hydrates are added with basic solutions, such as NaOH or NH 4 OH. CaCO 3 particles of different sizes and morphologies can be produced by either mechanical (milling) or chemical routes [33]. The mechanical route often produces a mixture of vaterite, aragonite, and calcite and requires a long processing time to reduce the particle size below 1 µm.…”

Section: Direct-precipitation Methodsmentioning

confidence: 99%

Liquid-phase synthesis of nanoparticles and nanostructured materials

Karatutlu

Emerging Applications of Nanoparticles and Architecture Nanostructures

Sapelkin

2018

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CHAPTER 1 Liquid-phase synthesis of nanoparticles and nanostructured materials on changing their physical properties; (7) size and shape of NPs and nanostructures could be controlled quite well by the most liquid-phase synthesis methods (depending on the method used). Chemical purification and size separation techniques, such as chromatography and high-performance liquid chromatography (HPLC) are not required; (8) postsynthesis techniques are available for formation of clusters [6] and 2d superlattices [7] from the as-prepared NPs and nanostructures. The liquid-phase synthesis can be classified into: (1) top-down approaches, where bulk materials are etched in an aqueous solution for producing NPs or nanostructures, for example, the synthesis of porous silicon by electrochemical etching; and (2) bottom-up approaches, where atoms/molecules via self-assembly, in general, are gathered together to form NMs and mixed in a controlled fashion to form a colloidal solution (Fig. 1.2). NPs produced by liquid-phase synthesis methods can remain in liquid suspension for further use or may be collected by filtering or by spray drying to produce a dry powder. Liquid-phase synthesis methods from a solution of chemical compounds include, but are not limited to, chemical stain etching, colloidal methods, coprecipitation, electrochemical deposition, direct precipitation, sol-gel processing, microemulsions method, reverse micelle synthesis, hydrothermal synthesis, template methods, polyol method, and laser ablation. In this ■ ■ FIGURE 1.2 Schematic of the formation of NMs processes. Top-down versus bottom-up liquid-phase synthesis methods. ■ ■ FIGURE 1.1 Various methods for formation of NMs. The liquid-phase synthesis is reported as one of the most widespread synthesis technique together with the gas-state synthesis.